FACTOID # 21: 15% of Army recruits from South Dakota are Native American, which is roughly the same percentage for female Army recruits in the state.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Ultra wideband

Ultra-wideband (also UWB, and ultra-wide-band, ultra-wide band, etc.) may be used to refer to anything with a very large bandwidth (e.g.: a type of sampling rate in the Speex speech codec). This article discusses the meaning in radio communications. Speex is a free software speech codec that claims to be unencumbered by patent restrictions. ... Speex is a free software speech codec that claims to be unencumbered by patent restrictions. ... Speech coding is the compression of speech (into a code) for transmission with speech codecs that use audio signal processing and speech processing techniques. ... Radio transmition diagram and electromagnetic waves For other uses see: radio (disambiguation) Radio is a technology that allows the transmission of signals by modulation of electromagnetic waves with frequencies below those of light. ...

Contents


Overview

Ultra-Wideband (UWB) is a technology for transmitting information spread over a large bandwidth that should, in theory and under the right circumstances, be able to share spectrum with other users. A February 14, 2002 Report and Order by the Federal Communications Commission authorizes the unlicensed use of UWB in 3.1 - 10.6 GHz. This is intended to provide an efficient use of scarce radio bandwidth while enabling both high data rate personal-area network (PAN) wireless connectivity as well as longer-range, low data rate applications as well as radar and imaging systems. More than 4 dozen devices have been certificated under the FCC UWB rules, the vast majority of which are radar, imaging or positioning systems. Deliberations in the ITU-R have resulted in a Report and Recommendation on UWB in November of 2005. National jurisdictions around the globe are expected to act on national regulations for UWB very soon The FCCs official seal. ...


Ultra-Wideband was traditionally accepted as impulse radio, but the FCC and ITU-R now defined UWB in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% bandwidth. Thus pulse-based systems wherein each transmitted pulse instantaneously occupies a UWB bandwidth, or an aggregation of at least 500 MHz worth of narrow band carriers, for example in OFDM fashion, can gain access to the UWB spectrum under the rules. Pulse may be sent at low pulse repetition rates, or they can be sent at very high repetition rates. Pulse based radars and imaging system tend to use low repetion rates, typically in the 1 to 10 megapulse per second range, while communications systems favor high repetition rates, typically in the 1 to 2 Gigapulses per second range, thus enabling short range gigabit per second communications systems. Each pulse in a pulse-based UWB system occupies the entire UWB bandwdith, thus reaps the benefits of relative immunity to multipath fading (but not to intersymbol interference), unlike carrier based systems that are subject to both deep fades and to intersymbol interference.


The FCC power spectral density emission limit is the same as for unintentional emitters in the UWB band, but is signficantly lower in certain segments of the spectrum.


Possible Applications

Due to the extremely low emission levels, UWB systems tend to be short range. However, due to the short duration of the UWB pulses, extremely high data rates are possible, and data rate can be readily traded for range by simply scaling the number of pulses per data bit. Conventional OFDM technology can also be used subject to the minimum bandwidth requirement of the regulations. High data rate UWB can enable wireless monitors, the transfer of data efficiently from digital camcorders, enable wireless printing of digital pictures from a camera without the need of an intervening personal computer, and the transfer of files among cell phone handsets and other handheld devices like personal digital audio and video players. Orthogonal frequency-division multiplexing (OFDM), also sometimes called discrete multitone modulation (DMT), is a complex modulation technique for transmission based upon the idea of frequency-division multiplexing (FDM) where each frequency channel is modulated with a simpler modulation. ...


See also

This article is about the Bluetooth wireless specification. ... Wireless is an old-fashioned term for a radio receiver, referring to its use as a wireless telegraph; now the term is used to describe modern wireless connections such as in cellular networks and wireless broadband Internet. ... A computer network is a system for communication between computers. ... Bandwidth is a measure of frequency range, measured in hertz, of a function of a frequency variable. ... A Fat Pipe is a data transmission circuit or network that is capable of carrying large amounts of data without significantly degrading the speed of transmission. ... Wideband is a relative term used to describe a wide range of frequencies in a spectrum. ... ZigBee is the name of a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802. ...

External links

  • The Ultra-Wideband Radio Laboratory at the University of Southern California has many publications including "Low noise amplifier design for ultra-wideband radio" by Jongrit Lerdworatawee, Won Namgoong, 2003
  • uwbforum The uwbforum is an open, non-profit industry association dedicated to collaboratively developing and administering specs from the physical layer up; enabling connectivity and interoperability for multiple industry-based protocols.
  • UWB Radio Technology Primer on UWB
  • WiMedia Alliance The WiMedia Alliance is an open, non-profit industry association dedicated to collaboratively developing and administering specs from the physical layer up; enabling connectivity and interoperability for multiple industry-based protocols sharing the MBOA-UWB spectrum.
  • UWB Info and resources
  • FCC Docket file on UWB

Chip manufacturers

Semiconductor companies providing complete solutions for Certified Wireless USB and Bluetooth 3.0, based upon the WiMedia ultra-wideband (UWB) technology

Software Providers

  • Microsoft Microsoft Windows Drivers (including WHCI - wireless host controller interface)
  • Stonestreet One Windows and Embedded drivers for UWB Hardware

  Results from FactBites:
 
ultra wideband - a Whatis.com definition (363 words)
Ultra wideband (also known as UWB or as digital pulse wireless) is a wireless technology for transmitting large amounts of digital data over a wide spectrum of frequency bands with very low power for a short distance.
Ultra wideband can be compared with another short-distance wireless technology, Bluetooth, which is a standard for connecting handheld wireless devices with other similar devices and with desktop computers.
Ultra wideband broadcasts digital pulses that are timed very precisely on a carrier signal across a very wide spectrum (number of frequency channels) at the same time.
Ultra-wideband - Wikipedia, the free encyclopedia (973 words)
National jurisdictions around the globe are expected to act on national regulations for UWB very soon.
Ultra Wideband was traditionally accepted as impulse radio, but the FCC and ITU-R now define UWB in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% bandwidth.
Thus, pulse-based systems—wherein each transmitted pulse instantaneously occupies a UWB bandwidth, or an aggregation of at least 500 MHz worth of narrow band carriers, for example in orthogonal frequency-division multiplexing (OFDM) fashion—can gain access to the UWB spectrum under the rules.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m